Dipyrromethane-Based PGeP Pincer Germyl Rhodium Complexes

A family of germyl rhodium complexes derived from the PGeP germylene 2,2'-bis(di-isopropylphosphanylmethyl)-5,5'-dimethyldipyrromethane-1,1'-diylgermanium(II), Ge(pyrmPⁱ Pr₂ )₂ CMe₂ (1), has been prepared. Germylene 1 reacted readily with [RhCl(PPh₃ )₃ ] and [RhCl(cod)(PPh₃ )] (cod=1,5-cyclooctadiene) to give, in both cases, the PGeP-pincer chloridogermyl rhodium(I) derivative [Rh{κ³ P,Ge,P-GeCl(pyrmPⁱ Pr₂ )₂ CMe₂ }(PPh₃ )] (2). Similarly, the reaction of 1 with [RhCl(cod)(MeCN)] afforded [Rh{κ³ P,Ge,P-GeCl(pyrmPⁱ Pr₂ )₂ CMe₂ }(MeCN)] (3). The methoxidogermyl and methylgermyl rhodium(I) complexes [Rh{κ³ P,Ge,P-GeR(pyrmPⁱ Pr₂ )₂ CMe₂ }(PPh₃ )] (R=OMe, 4; Me, 5) were prepared by treating complex 2 with LiOMe and LiMe, respectively. Complex 5 readily reacted with CO to give the carbonyl rhodium(I) derivative [Rh{κ³ P,Ge,P-GeR(pyrmPⁱ Pr₂ )₂ CMe₂ }(CO)] (6), with HCl, HSnPh₃ and Ph₂ S₂ rendering the pentacoordinate methylgermyl rhodium(III) complexes [RhHX{κ³ P,Ge,P-GeMe(pyrmPⁱ Pr₂ )₂ CMe₂ }] (X=Cl, 7; SnPh₃ , 8) and [Rh(SPh)₂ {κ³ P,Ge,P-GeMe(pyrmPⁱ Pr₂ )₂ CMe₂ }] (9), respectively, and with H₂ to give the hexacoordinate derivative [RhH₂ {κ³ P,Ge,P-GeMe(pyrmPⁱ Pr₂ )₂ CMe₂ }(PPh₃ )] (10). Complexes 3 and 5 are catalyst precursors for the hydroboration of styrene, 4-vinyltoluene and 4-vinylfluorobenzene with catecholborane under mild conditions.